This application claims Paris Convention priority of DE 199 20 614 filed May 5, 1999 the complete disclosure of which is hereby incorporated by reference.
The invention concerns a packaging machine comprising a package transporting means, in particular a folding box transporting means, and a transverse pushing means comprising a plunger which can be displaced substantially perpendicularly to the transport direction of the package transporting means, by means of which a package disposed on the package transporting means can be displaced perpendicularly to the transport direction, wherein the plunger is displaceably borne on an endless transporting means circulating substantially parallel to the transport direction of the package transporting means and at the same speed, wherein a cam track defines the displacement of the plunger and comprises a first section for axial extension of the plunger and a subsequent second section for axial retraction of the plunger.
A packaging machine for packaging a product into a folding box usually comprises an endless circulating package transporting means, e.g. a so-called folding box chain, and an endless circulating transport device for the products, e.g. a so-called product chain. The motion of the folding box chain and that of the product chain are synchronized for insertion of the product into the folding box transverse to the direction of motion of the chains.
Before inserting the products, a preceding operation ensures that the side closure flaps of the folding box on the inserting side of the product do not impede the inserting motion. This is usually achieved by displacing the folding boxes, disposed on the folding box chain, transverse to the transport direction of the folding box chain and one after another by using a plunger of a transverse pushing device, wherein the side closure flaps disposed on the inserting side of the product abut against guiding stops and are sidewardly displaced. Since the folding box has a relatively unstable shape during transverse displacement due to the open sideward closure flaps, abutment of the plunger against the folding box must be highly accurate. Matching of the axial extension and retraction of the plunger to the transverse transport motion of the folding box to be displaced is very difficult and frequently causes problems.
After transverse displacement of a folding box by the plunger, the plunger returns to its retracted original position from which it is again extended to transversely displace the next folding box. This reciprocating motion of the plunger requires a relatively large amount of time and substantially limits the cycle frequency and thus the overall output of the packaging machine.
U.S. Pat. No. 4,159,610 discloses a plunger, borne for displacement on an endless circulating transport device comprising chains extending substantially parallel to the transport device of the package transporting means. The transport device has transverse grooves disposed in regular intervals, in which transverse pushing elements (acting as plungers) are displaceably accommodated. Each plunger comprises a roller travelling in a guiding rail forming a cam track for defining the displacement of the plunger. The plunger exerts a pushing or extending motion perpendicular to the transport device and a correspondingly opposite retraction and is also displaced through a section, together with the transport device, parallel to the package transporting means in the transport direction, wherein the transport device and the package transporting means are preferably moved at the same speed to prevent relative displacement between the plunger and the package in the transport direction during the time at which the plunger moves, together with the transport device, parallel to the package transporting means. During motion in the transport direction, the plunger follows the cam track which determines the axial displacement, i.e. extension and retraction of the plunger.
At the end of the endless circulating transport device, the plunger returns to its original position opposite to the transport direction of the package transporting means and can therefore initiate transverse displacement of another package on the package transporting means.
The transport device comprises a toothed belt or a chain having, at an outer side thereof, a guiding part for the plunger in which it is accommodated for axial displacement.
The design of the transport device as an endless belt or strap extending parallel to the package transporting means permits the mounting of several equally spaced guiding parts, each having one plunger, on the belt or strap or on the transport device, to thereby increase the output of the packaging machine.
The cam track defining axial adjustment or displacement of the plunger comprises a first section for the axial extension of the plunger and a second subsequent section for the axial retraction of the plunger, each formed by a section of the guiding rail. To adjust the axial extension of the plunger for displacement with a different folding box format, the entire guiding rail must be removed and replaced. This makes format changes time-consuming and expensive.
It is the underlying purpose of the present invention to provide a transverse pushing device in a packaging machine of the mentioned kind which permits simple and rapid adjustment to the format of the folding box to be displaced.
This object is achieved in a packaging machine of the above mentioned kind by providing at least the first section of the cam track with an adjustable abutment surface on which a first roller travels. The initial position of the plunger and/or its axial extension can thereby be adjusted to the format of the folding boxes to be displaced.
Simple adjustment of the first section of the cam track can be achieved by forming the adjustable abutment surface from a spring steel plate which can be elastically deformed.
The second section of the cam track which determines the axial retraction of the plunger must not normally be adjusted to the respective folding box size. This second section is therefore preferably formed by a stationary guide, in particular, in the shape of a guiding groove in which the first roller runs.
Smooth, continuous transition must be ensured between the first section of the cam track formed by the spring steel plate and the second section of the cam track formed by the guiding groove. This is achieved in accordance with the invention in that the spring steel plate is mounted in the transition region between the first section and the second section of the cam track such that the surface of the spring steel plate always passes over smoothly into a wall of the guiding groove even when the spring steel plate is adjusted, wherein the spring steel plate accepts the axial motion caused by the adjustment. For adjustment of the spring steel plate, the initial region of the first section of the cam track opposite the retained end is borne on a holder, adjustable in the axial direction of the plunger.
Adjustment of the holder in the axial direction of the plunger changes the initial region of the first section of the cam track, i.e. of the spring steel plate, which leads to deformation of the spring steel plate, since it is fixed at its other end. This guarantees a continuous abutment surface in the first section of the cam track for all adjustment positions.
The extension and retraction of the plunger is preferably carried out via the first and second sections of the cam track when the plunger is located proximate the upper transport region of the endless circulating transport device. At the end of retraction the plunger is at the end of the upper transport region of the transport device and is deflected during further motion to move along the lower transport region and back to the beginning of the upper transport region. During this return motion in the lower transport region, the plunger is controlled in a third section of the cam track which guides the plunger during return motion of the circulating transport device. This third section is preferably formed on the spring steel plate such that, in the transition region between the lower transport region and the upper transport region, a continuous abutment surface is provided on a uniform spring steel plate. The spring steel plate is retained or clamped in a transition region between the guiding groove forming the second section of the cam track and the subsequent third section of the cam track to achieve secure mounting of the spring steel plate with the third section being borne on the holder at its opposite end region. The third section of the cam track preferably passes over smoothly into its first section,
It is advantageous to use two rollers for following the cam track during the extension of the plunger and during the return motion of the circulating transport device. The invention thereby provides that a first roller follows the first and third sections of the cam track on one side of the spring steel plate and a second roller seats on the opposite side of the spring steel plate. In this fashion, the axial displacement or position of the plunger is reliably defined. The second section of the cam track, i.e. in the guiding groove provides engagement for the first roller only and precisely defines the axial adjustment motion of the plunger.
The transport device is preferably a toothed belt whose outer side bears a guiding part for the plunger and comprises several equally distanced plungers.
Further embodiments and features of the invention can be extracted from the following description of an embodiment with reference to the accompanying drawings.